Bioenergetics: Anaerobic Pathway

Bioenergetics is primarily the process of conversion of macro nutrients—carbohydrate, protein, and fats into biologically usable forms of energy. It is this flow of energy within the biological system of our bodies that takes the chemical energy within macronutrients, and converts into ATP to drive muscular activity and growth. Thus, we need to have a basic understanding of how ATP is generated and used to drive muscular activity and muscle growth. The basic chemical reaction for this ATP generation is:

ATP + H2O <—ATPase—> ADP + Pi + H+ + Energy

Muscles store limited amount of ATP. Body stores about 3 ounces of ATP at any time. Not much. So, for muscle activity to continue, ATP-producing processes must occur. We need ATP to create the energy to do work that eventually enables muscle action How do we get this ATP? Three ways.

1. Phosphagen system
2. Glycolysis
3.Oxidative system

Depending on intensity and duration of activity, all three of these processes play a role to create energy. The phosphagen system is known as the anaerobic pathway, since it does not need oxygen molecules to create energy. The other two systems require the presence of oxygen as a substrate in order to create energy. Of the three main macronutrients, only carbohydrates can be used in the anaerobic metabolism.The phosphagen system is primarily engaged during short-term, high-intensity activities such as resistance training. However, the phosphagen system is actually active at the beginning of any activity, regardless of intensity level. As intensity decreases, and/or duration increases, the body shifts to the glycolytic and oxidation systems as its energy sources. But at no time is only one system solely at work to provide energy.

When ATP broken down to create energy, the ADP that is also a product is then synthesized with CP to create more ATP, as in this equation:

ADP + CP <—Creatine kinase—> ATP + Creatine

Once energy from the anaerobic pathway is depleted, then the body converts over to the aerobic pathway as its main source for energy. The aerobic pathway will be discussed in the next blog. But a couple points which differentiates these two pathways are that the anaerobic pathway can create energy fast, but it is depleted just as quickly. The aerobic pathway(s) create energy more slowly, but this system can sustain itself creating energy for a much longer time.